Supporting user designs of 3D contents remains a challenge in geometric modeling. Various modeling tools have been developed in recent years to facilitate architectural designs and artistic creations. However, these tools require both modeling skills and raw creativity. Instead of creating models from scratch, one of the most popular choices is to extract intrinsic patterns from exemplar inputs (e.g., shape collections and sketches), to produce creative models while preserving the patterns. The mod- eling process contains two main stages, analysis and synthesis. The analysis of input models is usually performed at component level, especially for man-made objects that can be decomposed into several semantic parts, for example, the seat and handles of a bicycle. The synthesis stage recombines parts of shapes to generate new models that usually have topological or geometric variations. In this thesis, we propose three design tools aimed at easing the modeling process. We focus on man-made objects and scenes such as buildings and furniture, as the functionality of such shapes can be analyzed at the component level. A relation graph, which is commonly used in shape analysis, can then be built to represent the input shapes. In our work, the graph nodes denote the elements of a model (i.e., rooms, shape parts, and strokes respectively), while the edges capture the intrinsic relations between connected elements. With the use of graph representations, we extract and present controllable components to users for supporting their designs. The emphasis of our work is on three aspects. Firstly, we propose a framework for supporting interior layout design, which allows users to manipulate the produced floor plans, i.e., changing the scales of rooms and their positions as well. When the user modifies the topology of a layout, the corresponding layout graph is updated and the room geometries are optimized under certain constraints, e.g., user specified scales, the adjacency of rooms, and fabrication considerations (i.e., economic construction cost). Secondly, we introduce replaceable substructures as arrangements of shape components that can be interchanged while ensuring boundary consistency. Based on the shape graphs that encode the structures of input models, we propose new automatic operations to discover replaceable substructures across models or within a model. We enforce a pair of subgraphs matching along their boundaries so that switching two subgraphs results in topological variations. Thirdly, we develop an interactive system that supports a freeform design by interpreting user sketches. 3D contents can be extracted from input strokes with or without user annotations. Our system accepts user strokes, analyzes their contacts and vanishing directions with respect to an anchored image, and projects 2D strokes to 3D space via a multi- stage optimization on spatial canvas selection. We demonstrate the computational approaches on a range of example models and design studies.

In a roadway network, infrastructure conditions determine efficient network operation and traveler safety, and thus roadway engineers need a sophisticated plan to monitor and maintain network performance. Developing a comprehensive maintenance and rehabilitation (M&R) strategy for an infrastructure system, specifically a roadway network, is a complicated process because of the system uncertainties and multiple parties involved. Traditional approaches are mostly top-down, and restrict the decision-making process. In contrast, agent-based models, a bottom-up approach, could well simulate and analyze the autonomy of each party and their interactions in the infrastructure network. In this thesis, an agent-based model prototype was developed to simulate the operations of a small roadway network with a high degree of simplification. The objective of this study is to assess the applicability of agent-based modeling for infrastructure management problems through the following four aspects: (1) to simulate the user route selection process in the network; (2) to analyze the impact of users’ choices on the congestion levels and structural conditions of roadway sections; (3) to help the engineer to determine M&R strategies under a certain budget; and (4) to investigate the impact due to different fare rates of the toll road section on the infrastructure conditions in the network. This prototype detected traffic flow, and gave appropriate M&R advice to each roadway segment. To improve this model, more investigation should be conducted to increase the level of sophistication for the interaction rules between agents, the route selection, and the budget allocation algorithm. Upon completion, this model can be applied to existing road networks to assist roadway engineers in managing the network with an efficient M&R plan and toll rate. / text

Radical polymerisation (RP) has for many years been an industrially important process, and the kinetics of the process remains an active area of research. As polymerisation proceeds, converting monomer (small molecules) into polymer (long chain molecules), chemical species of a variety of chain lengths are produced. Recent work has pointed toward the fact that rate coefficients for polymerisation reactions (specifically, termination and propagation) are often dependent on the chain-length of the reacting species. The focus of this thesis is to study the effects of chain-length-dependent reactions on the kinetics of RP, by using computer-based modeling and comparing the results of such modeling with experimental data. This enables the understanding of otherwise inexplicable trends and the building of more mechanistically detailed and accurate models for RP kinetics. In Chapter 2, a new model for termination is developed, connecting observations and analyses of termination kinetics at short chain lengths (particularly small molecule studies) with other observations and analyses at long chain lengths (conventional RP kinetics studies) in order to construct a model for termination that is shown to be capable of coherently describing termination kinetics at any chain length. In Chapter 3, this new model for termination is tested at short chain lengths on polymerisations with large quantities of added chain transfer agent. With the inclusion of chain-length-dependent propagation in the model, the model for termination is validated. Chapter 4 is aimed at extending an existing reduced-variable, compact, 'universal' description of steady-state RP kinetics by incorporating all known chain-length dependent reactivities. This both increases computational efficiency over other approaches and provides easily evaluated, approximate analytical expressions for RP kinetics. This foundational theory is applied in Chapter 5 to reach a deeper understanding of the behaviour of the model, and show how experimental data may readily be analysed to extract information about chain-length-dependent termination kinetics. In Chapter 6, the effect of chain-length dependent reactivities on the important technique of single-pulse pulsed-laser polymerisation is investigated, and this technique is validated as the best experimental method for investigation of termination kinetics. In general, a central result of this thesis is that chain-length-dependent reactivities, when acknowledged and properly incorporated into models, can explain many phenomena in RP kinetics which otherwise seem difficult to account for. No exceptions to this principle have been found.

Social-ecological systems (SES) may become “locked in” particular states or configurations due to various constraints on adaptability imposed by feedback mechanisms or by processes designed to incentivize certain behavior. While these locked-in states may be desirable and robust to disturbances over relatively short time periods, limits on system adaptations may diminish the longer-term resilience of these states, and potentially of the system itself. The agricultural SES in the Iowa-Cedar River Basin in eastern Iowa is one such system. While highly productive, culturally important, and essential to local economies, the system is facing significant economic and environmental challenges. This dissertation presents the results of a project designed to survey the adaptability of farmers in the ICRB, model their actions subject to constraints, and plot potential future states under scenarios of climate change, policy, and market conditions. We utilize a coupled agent-based model (ABM) to examine the specified resilience of the system to future climate, leveraging the ability of ABMs to integrate heterogeneous actors, dynamic couplings of natural and human systems, and processes across spatiotemporal scales. We find that farmer behavior is primarily constrained by economic factors, including federal crop insurance subsidies and the financial risk of implementing different crops or practices. Finally, we generate alternative system trajectories by modeling twenty-one scenarios, identifying actionable adaptations and pathways for transforming the system to alternative, more sustainable states.

This thesis presents the development of a hydrologic model in the vector environment. Establishing spatial relationship between flow elements is the key for flow routing techniques. Such a relationship is called hydrologic topology, making each flow element know which other elements are upstream and which are downstream. Based on the hydrologic topology established for the flow elements, tools were developed for flow network navigation, drainage area estimation, flow length calculation and drainage divide determination. To apply the tools, data required might be obtained from different sources, which may lead to certain problems that have to do with wrong flow direction of stream lines and, mismatches in location of stream lines with respect to the corresponding drainage area polygons. Procedures to detect such inconsistencies and to correct them have been developed and are presented here. Data inconsistencies correction and parameter computation methods form the basis for the development of a routing model, which would be referred as hydrologic model. The hydrologic model consists of an overland flow routing module, two options for channel routing and a reservoir routing module. Two case studies have been presented to show the application of the tools developed.

This research examines an approach for capturing 3D surface and structural data of moving articulated creatures. Given the task of non-invasively and automatically capturing such data, a methodology and the associated experiments are presented, that apply to multiview videos of the subjects motion. Our thesis states: A functional structure and the timevarying surface of an articulated creature subject are contained in a sequence of its 3D data. A functional structure is one example of the possible arrangements of internal mechanisms (kinematic joints, springs, etc.) that is capable of performing the motions observed in the input data. Volumetric structures are frequently used as shape descriptors for 3D data. The capture of such data is being facilitated by developments in multi-view video and range scanning, extending to subjects that are alive and moving. In this research, we examine vision-based modeling and the related representation of moving articulated creatures using Spines. We define a Spine as a branching axial structure representing the shape and topology of a 3D objects limbs, and capturing the limbs correspondence and motion over time. The Spine concept builds on skeletal representations often used to describe the internal structure of an articulated object and the significant protrusions. Our representation of a Spine provides for enhancements over a 3D skeleton. These enhancements form temporally consistent limb hierarchies that contain correspondence information about real motion data. We present a practical implementation that approximates a Spines joint probability function to reconstruct Spines for synthetic and real subjects that move. In general, our approach combines the objectives of generalized cylinders, 3D scanning, and markerless motion capture to generate baseline models from real puppets, animals, and human subjects.

With the proliferation of new technological alternatives to the traditional classroom, it becomes increasingly important understand the role that innovative technologies play in learning. Computer environments for learning to teach have the potential to be innovative tools that improve the skill and effectiveness of pre-service and in-service teachers. There is a tacit sense in such environments that “realism” is best created through, and associated with, a kind of pictorial literalism. I designed a computer model (the Direct Instruction tool) that, though simple, appears realistic to many users and thus contradicts that sense of literalism. I also propose a theoretical classification of computer representations based on the relationship (or lack thereof) between perceived usefulness or relevance and realism. In this study, I investigate two questions: 1) What are the kinds of claims or insights that respondents generate in relation to using the DI tool to organize their experiences? 2) How do the functionalities of the DI tool fit with or support what respondents see as meaningful? Results indicate that a model can be seen as relevant and useful even if it is not internally consistent. Two major themes that were meaningful to study participants were the simultaneously positive and negative role of “difficulty” in the classroom, and the balance between past performance and future potential. The DI tool seems to promote a shared focus on these themes despite the diversity of past educational experiences among study participants. Responses to this model suggest that extremely abstracted representations of teaching are able to influence the claims and insights of users, affording a glimpse into the internal realities of pre-service teachers. This in turn creates an opportunity to articulate these alternative realities without judgment, describe them with respect, and make them an object of consideration rather than a hidden force. The results of this study contribute to a theory of computer environments for learning to teach that can shape the effective use of these tools in the present, as well as accommodate new models that may be developed as technologies change in the future. / text

The Hohokam Water Management Simulation (HWM) is a computer simulation for exploring the operation of the Hohokam irrigation systems in southern Arizona. The simulation takes a middle road between two common kinds of archaeological simulation: large-scale, detailed landscape and environmental reconstructions and highly abstract hypothesis-testing simulations. Given the apparent absence in the Hohokam context of a central authority, the specific aim of the HWM is approaching the Hohokam as a complex system, using principles such as resilience, robustness, and self-organization. The Hohokam case is reviewed, and general questions concerning how the irrigation systems operated are shown to subsume multiple crosscutting and unresolved issues. Existing proposals about the relevant aspects of Hohokam society and of its larger long-term trajectory are based on widely varying short- and long-term processes that invoke different elements, draw different boundaries, and operate at different spatial and temporal scales, and many rely on information that is only incompletely available. A framework for pproaching problems of this kind is put forward. A definition of modeling is offered that specifies its epistemological foundations, permissible patterns of inference, and its role in our larger scientific process. Invoking Logical Positivism, a syntactic rather than semantic view of modeling is proposed: modeling is the construction of sets of assertions about the world and deductions that can be drawn from them. This permits a general model structure to be offered that admits hypothetical or provisional assertions and the flexible interchange of model components of varying scope and resolution. Novel goals for archaeological inquiry fall from this flexible approach; these move from specific reconstruction to a search for more universal and general dynamics. A software toolkit that embodies these principles is introduced: the Assertion-Based Computer Modeling toolkit (ABCM), which integrates simulation with the logical architecture of a relational database, and further provides an easy means for linking models of natural and social processes (including agent-based modeling). The application of this to the Hohokam context is described, and an extended example is presented that demonstrates the flexibility, utility and challenges of the approach. An attached file provides sample output.

This thesis presents the development of a hydrologic model in the vector environment. Establishing spatial relationship between flow elements is the key for flow routing techniques. Such a relationship is called hydrologic topology, making each flow element know which other elements are upstream and which are downstream. Based on the hydrologic topology established for the flow elements, tools were developed for flow network navigation, drainage area estimation, flow length calculation and drainage divide determination. To apply the tools, data required might be obtained from different sources, which may lead to certain problems that have to do with wrong flow direction of stream lines and, mismatches in location of stream lines with respect to the corresponding drainage area polygons. Procedures to detect such inconsistencies and to correct them have been developed and are presented here. Data inconsistencies correction and parameter computation methods form the basis for the development of a routing model, which would be referred as hydrologic model. The hydrologic model consists of an overland flow routing module, two options for channel routing and a reservoir routing module. Two case studies have been presented to show the application of the tools developed.

Radical polymerisation (RP) has for many years been an industrially important process, and the kinetics of the process remains an active area of research. As polymerisation proceeds, converting monomer (small molecules) into polymer (long chain molecules), chemical species of a variety of chain lengths are produced. Recent work has pointed toward the fact that rate coefficients for polymerisation reactions (specifically, termination and propagation) are often dependent on the chain-length of the reacting species. The focus of this thesis is to study the effects of chain-length-dependent reactions on the kinetics of RP, by using computer-based modeling and comparing the results of such modeling with experimental data. This enables the understanding of otherwise inexplicable trends and the building of more mechanistically detailed and accurate models for RP kinetics. In Chapter 2, a new model for termination is developed, connecting observations and analyses of termination kinetics at short chain lengths (particularly small molecule studies) with other observations and analyses at long chain lengths (conventional RP kinetics studies) in order to construct a model for termination that is shown to be capable of coherently describing termination kinetics at any chain length. In Chapter 3, this new model for termination is tested at short chain lengths on polymerisations with large quantities of added chain transfer agent. With the inclusion of chain-length-dependent propagation in the model, the model for termination is validated. Chapter 4 is aimed at extending an existing reduced-variable, compact, 'universal' description of steady-state RP kinetics by incorporating all known chain-length dependent reactivities. This both increases computational efficiency over other approaches and provides easily evaluated, approximate analytical expressions for RP kinetics. This foundational theory is applied in Chapter 5 to reach a deeper understanding of the behaviour of the model, and show how experimental data may readily be analysed to extract information about chain-length-dependent termination kinetics. In Chapter 6, the effect of chain-length dependent reactivities on the important technique of single-pulse pulsed-laser polymerisation is investigated, and this technique is validated as the best experimental method for investigation of termination kinetics. In general, a central result of this thesis is that chain-length-dependent reactivities, when acknowledged and properly incorporated into models, can explain many phenomena in RP kinetics which otherwise seem difficult to account for. No exceptions to this principle have been found.